Cored ceramic article



Dec. 17, 1946. E. H. FISCHER CORED CERAMIC ARTICLE Filed April 6, 1943 wnnunnn lNvENToR Uge/M/ZFascen womm Patented Dec. 17, 1946 CORED CERAMIC ARTICLE Eugene H. Fischer, Derry, Pa., assigner to Westinghouse Electric Corporation, East Pittsburgh, Pa.,la corporation of Pennsylvania Application April 6, 1943, Serial No. 481,991

1 Claim. 1

The present invention relates to ceramic articles and, more particularly, to articles of nonporous electrical porcelain having conductors embedded therein as well as a method for producing such articles.

Frequently it is desired to have porcelain devices with conductors extending into them or through them, and the only practical method of producing them has been to drill holes through the article before tiring, and, after ring, extend a conductor into or through the hole. This is because electrical porcelain is usually fired, or vitriiied, at a temperature of the order of 2400 F., and at this temperature most metals suitable as conductors would melt. Also, preformed holes in the porcelain are subject to substantial shrinkage when red, and dimensional fidelity is very diflicult.

The present invention avoids these difficulties and, in addition, permits irregular or non-linear holes to be formed in the porcelain article, and these, of course, could not be formed by an ordinary drilling operation.

By way of example, the present invention will be described in connection with a distributor of an ignition system for an internal combustion engine. In the past, so far as applicant is aware, porcelain has not been used in this field. The most common material is organic insulation, such as Micarta or Bakelite, but organic materials have the disadvantage that a ashover between terminals, due for example to a moisture deposit or dirt, leaves a charred path which is conducting to some extent and may form a permanent conducting path between such terminals. This has been found particularly dangerous in connection with aviation engines where rapid changes in altitude cause moisture condensation on the distributor cap. The use of porcelain, however, which is inorganic, avoids the difficulty and permits much higher altitude operation of the plane.

Accordingly, it is an object of the invention to provide a molded ceramic article having embedded conductors therein which may follow a linear or non-linear path.

It is a further object of the invention to provide a method for manufacturing such porcelain articles, and

It is a specic object of the invention to pron duce a distributor of inorganic material for the ignition system of an internal combustion engine.

Referring to the drawing,

Figure 1 is a plan view of an ignition distributor constructed in accordance with the present invention;

Fig. 2 is a view in section taken on the line II-II of Fig. 1; and

Fig. 3 is aview in section taken on the line III- III of Fig. 1.

Referring more speciiically to the drawing, the device shown in Fig. 1 comprises a rotor 2 and a stator 4 with cooperating contacts to distribute the high tension energy from the magneto to the cylinders of an internal combustion engine. The circuit connections of the entire ignition system are omitted as they are not a part of the invention. However, the general form of distribu` tor shown and the circuit connections used with it are vwell understood to those versed in that art.

Referring to Figs. 2 and 3, the rotor is supported for rotation upon a shaft B in a usual manner and is provided with a central electrode or terminal 8 which is electrically connected through conductors 9 and I0 to terminals I2. In addition, there is provided a conducting ring i4 which is fed from a terminal I6 on the stator 4. This ring, referring to Fig. 3, is electrically connected by conductors I8 and 20 to rotor terminals 22.

In forming the rotor body, it is intended that the method disclosed in my Patent No. 2,301,939, issued November 1'7, 1942, and assigned to the Westinghouse Electric Corporation, will be used. This method contemplates, briefly, depositing a granulated porcelain mixture, having a predetermined amount of moisture, in a steel mold and forming the article with a steel die under substantial pressure. The resulting porcelain article has the same mechanical and electrical characteristics as wet-process porcelain, and, in addition, it has substantially better dimensional delity on ring.

In accordance with the method of the present invention, the holes through the porcelain article are formed by providing cores of a metal alloy, such as Woods metal, which has a melting point preferably between F. and 180 F. In practice, an amount of the granulated porcelain mix is inserted in the mold, and the metal cores are placed therein in proper position, as with a suitable template. The mold is then filled, with the lling material tamped around the cores, and the high-pressure die is applied to mold the distributor rotor. A similar procedure, of course, with a different set of dies may be used to mold the stator.

It may be desirable, in some instances, to omit a core for the vertically extending conductor 9, and to drill a hole for such conductor before normally operates-,ata temperature at which the metal alloy wil11meltv so that duringAv the dryingv operation, the metal cores liquefy and pour out leaving clean cored holes.

After drying, the porcelain article may be glazed or not, as desired, and the hole Wallsr may be glazed by pouring the glazing material. through them. After the article hasV been-red and coo-led, the conductors Il), i8, and 20.- may be formed by merely pouring a molten alloy, such as type metal, into them andfpermitting it toV harden. Before hardening, however, the terminals 8, I2 and 22 are placed in position. These terminals all haverearwardly projecting shanks 24' which are inserted into the molten metal.' and solidiedin position. In addition, the terminals are secured in position by soldering them against the. porcelain itself. This is done by providing a metallic glaze on the porcelain adjacent the end of the respective conductors and soldering the terminal' tov such glaze. This is av well understood operation in the art.

It Will be notedthat the projecting contact portion off the terminals l2 and 22 is eccentric with respect tothe conductor associated With it. This. is for the. purpose of' having the contact portion as close as. possible. to the edge ofi the d rotor without weakening the porcelain section at this point, as would occur if the conductors themselves were moved closer to such edges.

It should be apparent from the foregoing that many types of porcelain articles having metal inserts or electrical conductors may be produced in a relatively simple and satisfactory manner. In. the case ofelectrical circuits, they do not have tok be linear but may assume almost any conguration so long as there is suflicient porcelain interposed between circuits to afford the necessary insulating qualities. Also, by reason of the fact that: the holes through the porcelain piece arev completely filled with conducting material, thereV is. no possibility of corona discharge with its attendanty interference With radio reception. Further, the use of this method and porcelain,

Vasy distinguished from an organic material, re-

sultsin an improved electrical device where discharge between terminals does not result in damage to the surface of the device.

Quite obviously modications of the specic method' disclosed, and the specific porcelain article described, are possible, andV applicantl intends that the invention shall not be limited' except* as by the appended claim.

I claim as my invention:

In an electrical contact device, a body of nonporous porcelain having a hole therethrough fromv one face to another, av low-melting-point alloy filling said hole to constitute a through' conductor, and terminals for saidl conductor each having` a portion thereof embedded in said' alloy.

EUGENE H; FISCHER. 

